There are many types of pipe couplers known in the art of pipe coupling and the present invention is concerned with internal pipe couplers whereby to interconnect two pipes in end-to-end abutting relationship. An example of such a coupler is described in U.S. Pat. No. 2,850,304 wherein an internal expanding sleeve is located in opposed ends of two pipes placed in abutting end-to-end relationship and the coupler is in the form of channels with reversely turned flanges of arcuate form. A set screw is provided in the wall of one of the pipes and engages internally the bottom of the respective channels while the reversely bent flanges engage the inner surface of the pipe walls. With this type of device it is necessary to thread a bore in the side wall of one of the pipes adjacent an end thereof for receiving the set screw. Also, one of the channel members of the connector has a threaded bore which needs to be aligned with the set screw for connection thereto while the channel member is positioned inside the end of one of the pipes. This is a time consuming assembly and requires precision and skill to install. A further disadvantage of such connectors is that if the set screw becomes disconnected, the channel members inside the pipe would fall freely inside the pipe, particularly if they are disposed in a vertical or an angular relationship causing the pipes to be disconnected. Also, vibrations in the pipes can cause the set screw to loosen. Such a connector would not be desirable for interconnecting ends of piles which are driven into the ground by impact force, for example. Another disadvantage of such connector is that they utilise a connector consisting of two components plus a set screw. If one of these components or screw becomes lost then the connector cannot be assembled. This type of connector therefore is subject to human error.
US application 2005/0111920 A1 published on May 26, 2005 describes an apparatus and a method for installing segmented concrete pilings. The concrete pilings are interconnected together in end-to-end relationship by connecting rods. The concrete pilings are therefore provided with apertures and these connecting rods are positioned therein. This patent application is not concerned with interconnecting hollow pipes in end-to-end relationship by a connector capable of permitting the passage of liquid or loose flowable material therethrough from inside the pipes after the pipes are interconnected together or during a pile driving operation.
Another known method of interconnecting hollow pipes in end-to-end relationship is by welding the joint formed by the abutting pipe ends together. Accordingly, there is required the use of a welder person to effect this soldering operation which is a relatively slow and expensive process. Another known method is to connect a sleeve about the abutting pipe ends connecting both pipe ends together. This is not desirable when the pipes are used as pile cylinders which are driven into the ground surface as the sleeve would provide added friction with the soil during the pile driving operation and are subjected to damage. Such joints are not practical as they add too much friction to the outer surface of the pipes.